My buddy Carlo sent me a Squire J neck to replace the cheap P bass neck on TestBass (the bass I cycle all the pickups I make through to test them out). That P bass neck plays like a splintery 2X4, except maybe not as good.
I was looking forward to a nicer neck, except the neck Carlo sent had a pronounced ski-slope about 5 frets from the nut. Even tightening the truss rod to near infinity would barely take it out, and that was with no string tension.
So I remembered a trick I saw at Charvel's in Azusa in the late 70's, when it was in back of the strip club. They had a jig where you could clamp a bowed neck straight, then put a heat lamp on it. Kind of like steaming wood so that you can bend it.
I clamped my bowed neck to the workbench, with a shim so that I could actually reverse-bend it a little, and put a heat lamp on it (a chicken incubator, to be more exact). I watched the temp with my IR temp sensor gun (don't want to set no fires or bubble no finish) and held it at about 190F for about 30 minutes. Then I turned the heat off and let the neck cool in the clamped condition.
I took it out of the clamps, and wow, it was really straight! Hard to take a picture of though...
Now it is ready to make its acquaintance with Mr TestBass.